1) Field of the Invention
The present invention relates to optical-projection systems and, more particularly, to an optical-projection system for projecting flaws and inspection locations during the manufacture or assembly of a workpiece.
2) Description of Related Art
One method and device for assisting in the measurement of a workpiece includes the use of an image-projecting device, such as a laser projector, which projects a laser beam upon the workpiece to define particular locations at which to inspect the workpiece. Furthermore, image-projecting devices have been employed to aid workers during assembly and inspection of a workpiece. For instance, the image-projecting device could project the location of laminate plies for an aircraft fuselage or a template or outline of the part to be assembled.
Therefore, controlling or monitoring the orientation and location of the image-projecting device is required in order to accurately project the image onto the workpiece. Traditionally, projection technology either requires the measurement of reference points on the object being projected or a secondary measurement system to establish reference points if the references are arranged beyond the field-of-view of the image-projecting device. For example, U.S. Patent Application Publication No. 20050121422 to Morden et al. discloses a laser projection system that modifies the data stored in the computer associated with the laser projection of the as-designed workpiece to provide for projection of a laser image on the workpiece in the as-built condition. In particular, Morden employs a digital scanner and laser projector that are each mounted on a frame assembly having metrology receivers and reflective targets for determining the location of the scanner and projector relative to a respective frame assembly. Thus, the laser projection system is essentially “targetless,” as the workpiece does not require targets within the field-of-view of the digital scanner or laser projector, notwithstanding reflective targets on the frame assembly.
Additionally, U.S. Patent Application Publication No. 20040189944 to Kaufman et al. discloses a method and system for visualizing deviations on an actual surface. More specifically, Kaufman discloses visualizing surface shape errors by optically projecting a pattern outlining the areas that deviate from a desired design onto the surface. The system utilizes a laser tracker in conjunction with a retro-reflective element and reference points associated with the surface to produce a three-dimensional point cloud of data points that provide a spatial profile of the actual surface. The same reference points used by the laser tracker can also be measured by the image projecting device for computing its orientation and location. The point cloud is compared to a nominal surface, and a deviation is computed and transformed into a two-dimensional topographical map for projecting onto the surface with an optical projector.
Although techniques have been developed to determine differences between an as-designed periphery and an as-built periphery for assembly or locating areas on the workpiece for other purposes, such as painting, applying decals, etc., image-projecting systems are typically not employed to locate flaws on or within a workpiece. For example, typical projection systems are not employed to locate cracks, discontinuities, voids, or porosity, which could adversely affect the performance of the workpiece. Furthermore, typical image-projection systems are incapable of being used during manufacturing, such as during tape laying of composite plies onto a workpiece, to validate the integrity and fitness of the workpiece. Additionally, typical image-projection systems are incapable of being used to record feedback at the workpiece surface, such as information regarding the workpiece being inspected.
It would therefore be advantageous to provide an optical-projection system that is capable of locating flaws on or within a workpiece. In addition, it would be advantageous to provide an optical-projection system that is capable of locating flaws on or within the workpiece during a manufacturing process without requiring measurement of reference points. It would also be advantageous to project information indicative of the type of flaw on or within the workpiece. Furthermore, it would be advantageous to provide an optical-projection system that locates flaws and is capable of providing feedback regarding flaws on or within a workpiece.